An air distribution system may be used to direct air from one portion of an aircraft to another. In some aircraft configurations, the air distribution system includes an inlet duct that receives air from an air source and two or more outlet ducts that exhaust the received air to a desired area within the aircraft, such as, for example, to an aircraft cabin or an underfloor section of the aircraft. To maintain aircraft weight at certain requirements, the ducts typically have thin walls that are made from lightweight materials, such as wrapped composite. Conventionally, a flow splitter is positioned between the inlet and outlet ducts to distribute the air between the two or more outlet ducts. The flow splitter includes a butterfly valve that is coupled to an actuator that opens and closes the valve upon command from the aircraft control system. When the valve is closed, the air circulates through a first system that includes the inlet duct and one of the outlet ducts. Similarly, when the valve is open, the air circulates through a second system that includes the inlet duct and another one of the outlet ducts.
In rare instances in which the air flow experiences a sudden increase in flow rate, pressure on one side of the valve may exceed an acceptable level. Specifically, if the valve is closed, the ducts of the first system may experience an unwanted buildup of pressure. As a result, the pressure may need to be relieved. Typically, the butterfly valve is opened to allow air to flow through the second system; however, if the control system fails to command the butterfly valve to open, the pressure in the first system may increase to an unacceptable level. Consequently, the structural integrity of the thin-walled ducts may be compromised.
To overcome some of the above-mentioned drawbacks, a parallel duct system has been implemented into some aircraft. The parallel duct system is coupled to the air distribution system and directs air either overboard or to other sections of the aircraft when the pressure across the valve exceeds acceptable levels. However, this system, too, may have disadvantages. Specifically, the parallel duct system includes additional components which may increase the weight and/or manufacturing cost of the aircraft.
Accordingly, there is a need for an air distribution system that maintains structural integrity in the event of an unexpected airflow rate increase. In addition, there is a need for an air distribution system that is lightweight and relatively inexpensive to implement. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.